Seal for moving strip

ABSTRACT

A seal for the opening of a treatment chamber for treating moving strip. An elongated roll or mounting member is pivotally mounted in a housing on each side of the opening. An elongated contact roller is rotatably mounted to each of the roll members, the contact rollers being yieldably biased toward each other through pivotal movement of the roll members so as to engage opposite sides of the strip. A backup roller is rotatably mounted in each of the roll members engaging the respective contact roller. The contact and backup rollers pivot about the axes of the roll members to accommodate strips of varying thickness and/or including nonuniformities. Seals between the elongated roll members and the housing facilitate the overall seal that is required.

limited States Patent Main [45] Feb. 8, 1972 [54] SEAL FOR MOVING STRIP [2l] Appl. No.: 874,003

[52] U.S. Cl. ..277/237, 34/242, 277/DIG. 7 [5 l] Int. Cl... Fl6j 15/50 [58] Field of Search ..1l8/48-50.l, 404,

[56] References Cited UNITED STATES PATENTS 2,367,174 l/ 1945 Renkin ..34/242 3,001,390 9/1961 Zimmer ....118/405 X 3,291,468 12/ 1966 Albertsen et al ..34/242 X 3,334,908 8/1967 Starbuck ..277/237 R 3,51 1,065 5/ l970 Peter ..34/242 X Primary Examiner-Morris Kaplan Attorney-Robert P. Wright and Joseph W. Malleck [57] ABSTRACT A seal for the opening of a treatment chamber for treating moving strip. An elongated roll or mounting member is pivotally mounted in a housing on each side of the opening. An elongated contact roller is rotatably mounted to each of the roll members, the contact rollers being yieldably biased toward each other through pivotal movement of the roll members so as to engage opposite sides ofthe strip. A backup roller is rotatably mounted in each of the roll members engaging the respective contact roller. The contact and backup rollers pivot about the axes of the roll members to accommodate strips of varying thickness and/or including nonuniformities. Seals between the elongated roll members and the housing facilitate the overall seal that is required.

` "'"ims, 4 Drawing Figures SEAL son MovlNc STRIP BACKGROUND OF THE INVENTION The present invention relates to chambers for treating moving strips, and particularly to seals for the openings (entrance and exit) of such chambers.

In the vacuum coating of metal strip, for example, it is necessary to seal the entrance to and exit from a vacuum chamber. It is well known in the art to employ contact rollers to accomplish this result. See, for example, Starbuck, U.S. Pat. No. 3,334,908.

One difficulty with existing roller-type seals is that they are not instantaneously adjustable to strips or webs of varying thickness. See Albertson et al., U.S. Pat. No. 3,291,468. Sudden changes in material thickness may occur or the contact rollers themselves may expand or contract due to temperature fluctuations. Unless the rollers immediately respond to such changes, damage may result to the strip or web or contact rol- Iers.

In the Starbuck patent noted above, an attempt was made to overcome this problem by providing elastomeric coverings for the contact rollers. Such coverings are inadequate to allow for substantial variations in strip thickness. Thicker portions in the web may cause overloading of fixed journal bearings, deflection of the rollers, and man-ing of any coating deposited on the web.

Others have sought to resolve the problem by locating elongated rollers on planes disposed at acute angles to the direction of travel, the rollers being biased toward the strip or web. See Fahringer, U.S. Pat. No. 2,873,597. The rollers in those designs are intended to separate to accommodate varying thicknesses of web. Those seals are not effective, however, when the traveling web must move in a horizontal direction rather than in a downwardly direction, and there is a high coefficient of friction between the web and the rollers.

Walter U.S. Pat. No. 2,260,128 discloses a sealing means utilizing a spring mounted contact roller movable away from a strip. The response of this system to strip thickness changes is believed to be poor.

Therefore, it is desirable to provide for the efficient sealing of the entrance and exit of a treatment chamber while accommodating continuous strips or webs of varying thickness passing through the chamber.

SUMMARY OF THE INVENTION An object of the invention is to provide an improved seal for a chamber through which is moving web or strip passes.

Another object of the invention is to provide a seal which rapidly adjusts to accommodate a strip or web of varying thickness.

A further object of the invention is to provide a seal for a vacuum chamber or the like which does not damage a strip or web of material or any coating which may be deposited thereon in the chamber.

Still another object is to provide a seal through which a continuous strip or web may be readily threaded and which may be disposed vertically, horizontally, or at any angle to the apparatus to be sealed.

To these and other ends, the present invention contemplates sealing the opening to a treatment chamber through the use of an elongated roll or mounting member which provides a support for a seal-providing Contact roller. The elongated roll member is pivotally mounted adjacent the opening to the chamber. The contact roller is rotatably mounted to the roll member. The roll member is yieldably urged toward the opening to the treatment chamber so that the contact roller engages the strip passing through the chamber. The contact roller is covered with elastomeric material which permits minor variations in strip thickness to be accommodated without any substantial movement of the contact roller. However, any substantial change in strip thickness causes the contact roller to pivot about the pivotal support of the roll member, permitting such thickness variation to be immediately compensated for without damage either to the contact roller or to the strip.

The elongated roll member that carries the contact roller also may carry a backup roller which engages the contact roller. The backup roller serves as a rotatable seal for the contact roller and also acts as a heat sink for the contact roller. Seals are provided between the backup roller and the roll member and between the roll member and the frame that supports the roll member in order to provide for complete sealing of the treatment chamber. In this connection, by utilizing an elongated roll member, which is aslong as or longer than the maximum width of the strip to be treated (i.e., the roll member extends transversely of the strip), sealing between the roll member and the frame or housing therefor is easily achieved.

A roll member and associated contact and backup rollers are normally provided on both sides of the strip, so that the contact rollers engage opposite sides of the strip to provide a seal, yet both being pivotable away from the strip to accommodate variations in strip thickness.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view, partly in section, of representative sealing apparatus in accordance with the present invention:

FIG. 2 is a sectional view taken along the line 2-2 of FIG. l;

FIG. 3 is a side elevational view, partly in section, of a modified form of sealing apparatus in accordance with the present invention; and

FIG. 4 is a sectional view taken along the line 4-4 of FIG. 3.

DETAILED DESCRIPTION Referring to the drawings, there is shown apparatus for sealing the opening (entrance or exit) to a treatment chamber for a moving strip l0. The apparatus may be used, e.g., for vacuum or other chambers in which the interior pressure is maintained at a level different from the pressure in the areas adjacent to and opening into said chambers. The strip l0 is shown moving from left to right in FIG. 1, e.g. into or out of a treatment chamber. The apparatus shown is particularly useful in the coating of metal strips such as steel under vacuum.

A frame 12 includes an upper portion 14 and a lower portion 16 defining between them a central gap 18 through which the strip or web l0 may pass from frame inlet l5 to frame outlet 17. Frame wall 12a may be mounted to the inlet wall (not shown) of a treatment chamber, or wall 12b may be mounted to the outlet wall (not shown) of the chamber. It should be understood that the sealing apparatus is capable of use in any orientation, eg., horizontal or vertical. The terms upper and lower, when referring to the portions of the frame l2, are with respect to the orientation shown in FIG. 1.

A cavity 20 is formed in both the upper portion 14 and the lower portion 16 on either side of the gap 18 for purposes stated more fully below. Each cavity 20 is elongated and generally cylindrical in shape, the portion of the cavity 20 facing the gap 18 being open to the gap and transverse to the direction of travel ofthe strip.

In order to seal the chamber, a contact roller 22 is rotatably mounted in each of the cavities 20. The contact rollers 22 are relatively elongated and of substantially the same length as the cavities 20. The contact rollers 22 are normally biased toward touching engagement and are disposed across the gap 18 so that the moving strip 10 must force its way between the rollers in order to enter or leave the treatment chamber. The contact rollers 22 rotate about their longitudinal axes at a peripheral speed the same as the forward speed of the strip 10. Each of the contact rollers 22 is fitted with an elastomeric sleeve or covering 24. Employment of an elastomeric sleeve 24 allows the strip 10 to pass into or out of the chamber without being damaged; minor variations in strip thickness are accommodated by such sleeves. The sleeves 24 may be fabricated of any suitable rubber or rubberlike material having good wear resistance and toughness and capable of withstanding fairly high temperatures, e.g., up to 600 F.

A backup roller 26 is rotatably mounted in each of the cavities 20 and engages the associated contact roller 22. The backup roller 26 serves as a rotatable seal for the contact roller 22 and acts as a heat sink for the contact roller to remove heat transferred to the contact roller from the hot strip l passing through the seal. As suitable elastomeric sleeves 24 are capable of accommodating strip temperatures of up to only about 600 F., the backup roller 26 serves an important function in removing heat from the contact roller 22 when temperatures reach a level close to the upper service limit of the elastomer covering the roller. It is possible, however, to water-cool the unit if continuous use of high-temperature strip is contemplated. Each backup roller 26 is relatively elongated and of substantially the same length as the contact roller 22. The backup roller 26 is in longitudinal line contact with the contact roller 22 and is free to rotate therewith about its longitudinal axis.

ln accordance with the present invention, a pivotable roll or mounting member 28 is located in each of the cavities 20. The contact roller 22 and backup roller 26 are contained within the roll member 28. The roll members 28 and their respective cavities 20 have corresponding arcuate sections of substantially equal diameter, so that the roll members 28 may swivel or pivot about roll member axes 28a within the cavities upon displacement of the carried contact rollers 22. To increase the gap 18 through which the strip 10 travels, the contact rollers 22 pivot along with the respective roll members 28. Pivotal movement of the contact rollers 22 occurs since the longitudinal axis of each contact roller 22 is spaced from the longitudinal (pivoting) axis of the respective roll member 28. The greater the spacing between the axes, the more responsive the contact roller to deviations in strip thickness and the closer control exertable over movement of the contact rollers.

In the embodiment of the invention shown in FIGS. l and 2, the contact rollers 22 and the backup rollers 26 are disposed in the interior of the respective roll member 28 and are rotatably mounted at their ends in the roll member by means of bearings 30. In turn, each roll member 28 is pivotally mounted at its ends in a bearing plate 32 by means of a bearing 34. The roll members 28 are elongated (as long as or longer than the maximum width of the strip l0) and generally cylindrical in shape so as to fit within and substantially fill the cavities 20.

Normally, the longitudinal axes of both sets of contact rollers 22, backup rollers 26, and roll members 28 lie in a common plane transverse to the plane of the traveling strip l0. Each roll member axis 28a lies between the axes of the contact and backup rollers. A yieldable biasing device, such as a spring 36 or yieldable fluid system (not shown), is connected between a pin 38 extending from the bearing plate 32 and a pin 40 disposed through an axial extension 28h of the roll member 28 urges the contact rollers into position against the strip l0. An increase in thickness of' the moving strip l0 forces the contact rollers 22 outwardly against the force of the biasing device 36, however, thereby immediately accommodating such thickness variation. A stop 42 (including projection 42a) is engageable by the pin 40 to prevent back travel of the contact rollers 22. The pull of the biasing device 36 reduces the distance between the contact rollers 22 as the temperature drops or the thickness of the strip decreases.

Although the elastomer-covered contact rollers 22 substantially prevent pressure leakage between the contact rollers and both the strip and the backup rollers 26, they do not prevent leakage through other portions of the apparatus. In the embodiment of the apparatus shown in FIGS. l and 2, a seal 58, such as a spring-loaded rubbing bar or the like, is located along the entire length of the backup roller 26 within the roll member 28. Placement of this seal 58 between the backup roller 26 and the roll member 28 reduces pressure leakage around the rollers to a minimal amount. An additional elongated seal or spring-loaded rubbing bar 60 is disposed in the roll member 28 and contacts the frame l2 along the entire length of the roll member 28. Seal 60 therefore minimizes pressure leakage around the roll member 28. An end plate 62 (as best seen in FIG. 2) is bolted to the frame l2 so as to completely enclose the ends of the apparatus. An O-ring seal 64, located between the frame l2 and the end plate 62, prevents any leakage through the sides of the frame.

In operation ofthe apparatus of the embodiment of FIGS. 1 and 2, the traveling strip or web l0 moves through the gap I8 in the frame 12 between the frame inlet l5 and the frame outlet 17 when entering or leaving the chamber of treatment. The strip 10 passes between and is engaged by the elastomeric sleeves 24 of the contact rollers 22. If the strip l0 should in` crease or decrease in thickness, the contact rollers 22 will swivel about the pivotal axes of the roll members 28 so as to accommodate the thicker or thinner strip l0. Considerable movement of the contact rollers 22 is permitted against the force of the biasing device 36.

A modified form of apparatus in accordance with the present invention is shown in FIGS. 3 and 4. Similar to the embodiment of FIGS. 1 and 2, a frame l2 has an upper portion 14' and a lower portion 16' defining a gap 18' between them through which a moving strip or web l0 may pass. Contact rollers 22 disposed within opposing cavities 20' in the frame engage the strip l0 on both sides thereof' and have elastomeric sleeves 24. Backup rollers 26 also disposed within the cavities 20 are driven by the contact rollers 22 and act as heat sinks therefor.

A different type of roll member is employed in the modified version of the apparatus, however. The modified roll or mounting member 44 is elongated but does not contain the contact and backup rollers in a cylindrical shaft. Each roll member 44 comprises a roll 46 and a plate 48 rigidly mounted at each end of the roll 46 and extending therefrom toward the gap 18. The end of the plate 48 that is adjacent gap 18' has an arcuate portion 48a. The contact rollers 22 and backup rollers 26 are rotatably mounted at their ends by means of bearings 30 in the plate 48. The roll member 44 in turn is pivotally mounted by means of axial extension 44a mounted in bearing 34 in bearing plate 49 (the same structure is used at both ends of the roll member). The cavity 20 is provided near its opening to the gap 18' with an arcuate surface 20a of a diameter slightly greater than that of the arcuate portion 48a of the plate 48. The roll member 44 may pivot within the cavity 20 about the axial extension 44 a, which is coincident with the longitudinal axis of the roll 46. Since the contact roller 22 and backup roller 26 are journaled in each plate 48, they pivot along with the roll member 44 upon an increase in the thickness of the moving strip l0 which forces the contact rollers 22 apart. In this embodiment the spacing between the rotational axis of the contact roller 22 and the pivoting axis (the axis of roll member extension 44a) is greater than the spacing between the corresponding axes in the embodiment of FIGS. l and 2. In this case the axis of pivoting is greater distance from the gap I8' than either axis of' contact roller 22 or backup roller 26. Closer control may thus be maintained over the pivotal movement of the roll members 44 and hence over contact rollers 22, and material of low-tensile strength may be more readily accommodated.

All the rollers of the modified apparatus shown in FIGS. 3 and 4 are yieldably urged into positions in which their longitudinal axes lie in a common plane. A biasing device, such as a spring 50, yieldable fluid system (not shown) or the like, is

A seal of spring-loaded rubbing bar 66 is disposed between the backup roller 26 and the roll 46 of the roll member 44 along their entire lengths. Another seal or spring-loaded rubbing bar 68 is located between the roll 46 and the frame l2 along the entire length of the roll 46. As the roll member 44 does not occupy the entire volume of the cavity 20, it is necessary that an additional seal 70 be disposed about the ends of the rollers and the roll member 44. Preferably, the seal 70 is fabricated in three layers which are bonded together: an outer layer 72 formed of a rigid, hard material (such as steel, teflon or the like), a middle layer 74 formed of a resilient, soft material such as sponge rubber or the like, and an inner layer 76 formed of a rigid, hard material such as steel or teflon. The seal 70 tits about the axial extension 44a of the roll member 44 but is prevented from rotating therewith by a spacer 78 formed of brass or like material which is positioned between the axial extension 44a and the seal 70. The outer layer 72 of the seal 70 is pressed against the bearing plate 49 in which the roll member 44 is joumaled, and the inner layer 76 is against plate 48. The seal 70 serves to prevent leakage about the ends of the rollers. In order to prevent leakage about the side of the frame 12, an end plate 82 is bolted to the end of the frame 12 and an O-ring seal 84 is disposed between the frame l2 and the end plate 82. As the axial extension 44a in this embodiment extends through and beyond the end plate 82, an additional seal 86 is located about the axial extension 44a outside the end plate 82 to prevent leakage between the extension and the end plate. The biasing device 50 may be located outside the frame 12 as well. This makes it convenient to remove the biasing device S so that the strip 10 may be more easily threaded through the apparatus and also provides visual check of the seal in operation.

ln operation of the embodiment of the invention shown in FIGS. 3 and 4, a strip l0 travels (to the right in FIG. 3) in the gap 18' between the elastomeric sleeves 24 of the contact rollers 22 to enter or leave the treatment chamber. lf the strip l0 increases substantially in thickness so that the elastomeric sleeves 24 cannot totally absorb the thickness change, the contact rollers 22 will pivot (clockwise below gap 18 and counterclockwise above the gap) about the axes of the rolls 46 to accommodate the thicker strip. The spring 50 yieldably biases the contact rollers 22 against the strip 10 at all times.

It should be understood that the apparatus of the present invention may be used with strips or webs of any suitable width and thickness. Apparatus such as disclosed herein has been utilized in the vacuum treatment of strips of metal about l0 inches to l2 inches in width and about 0.060 inches in thickness. A central gap 18 (or 18') about one-half inch deep has been utilized. Strips or webs of considerable thickness and width may be accommodated. The apparatus may be used with strips of continuous width or with a plurality of strands or even with bars or tubes. Any type of such strip material may be processed.

The present invention thus provides apparatus for sealing the entrance and exit of a treatment chamber. The seal of the present invention rapidly responds to accommodate strips or webs of material of varying thickness without damaging the strip or web or any coating which may be deposited thereon or the contact rollers or support structure. The apparatus disclosed is capable of use in any orientation.

What is claimed is:

l. In a seal for a housing having a gap therein through which strip material passes, the combination comprising:

a. an elongated mounting member as long as the gap and pivotally mounted in said housing adjacent to said gap and yieldably urged to pivot in one direction about its pvot axis;

b. elongated Contact roller means rotatably mounted to said mounting member and yieldably urged toward said gap through said pivotal movement and yieldable urging of said mounting member for engaging the strip material to form a seal therewith; and

c. elongated seal means extending the length of said elongated mounting member and carried thereby and contacting said contact roller means to form a seal between said mounting member and said contact roller means.

2. A seal according to claim l, wherein said seal means comprises a backup roller rotatably mounted to said mounting member.

3. Apparatus according to claim 2, wherein said elongated seal means includes at least one seal between said backup roller and said mounting member.

4. Apparatus according to claim 3, further including atleast one elongated seal extending the length of said elongated mounting member between said mounting member and said housing.

5. Apparatus for sealing the opening to a vacuum treatment chamber for strip, comprising: l

a. a frame having an opening defining said opening to the chamber;

b. a pair of elongated mounting members at least as long as the maximum width of strip that can pass through said frame opening and pivotally mounted to said frame on opposite sides of said frame opening;

c. a pair of contact rollers on opposite sides of said frame opening and rotatably mounted to said mounting members;

' d. a pair of backup rollers positioned on opposite sides of said frame opening and rotatably mounted to said mounting members and engaging said contact rollers, each contact roller being positioned between said frame opening and the associated one of said backup rollers;

e. first seal means sealing the backup rollers to said mounting members;

f. second seal means sealing said mounting members to said frame; and

g. means yieldably urging said mounting members to pivot about the pivotal axes thereof so that said contact rollers mounted thereto are yieldably urged toward each other within said frame opening to yieldably engage said strip.

6. In a seal for a wall structure having an opening therein through which strip material passes, the combination comprismg:

a. a contact roller on one side of said opening for engaging one side of said strip;

b. a backup roller engaging said contact roller; and

c. a mounting member for mounting said contact and backup rollers, said mounting member being pivotable about an axis thereof to concomitantly move the rollers mounted thereby toward and away from said opening, said mounting member being yieldably biased about its pivot axis to yieldably urge the rollers toward said opening and said contact roller into yieldable engagement with said one side of said strip to form a seal therewith.

'i'. A seal according to claim 6, wherein the pivotal axis of said mounting member and the axes of rotation of said contact and backup rollers are parallel to each other and lie in a common plane.

8. A seal according to claim 7, wherein the pivotal axis of said mounting member is further away from said opening than the axes of rotation of said contact and backup rollers.

9. A seal according to claim 7, wherein the pivotal axis of said mounting member is between the axes of rotation of said contact and backup rollers.

l0. Apparatus according to claim 6, wherein said backup and contact rollers have their ends joumaled in end portions of said mounting member.

ll. Apparatus according to claim 6, wherein said mounting member is cylindrical and includes channels longitudinally therein in which said contact and backup rollers are positioned.

12. Apparatus according to claim 6, wherein said mounting member is cylindrical and includes end plates at the ends thereof, the pivotal axis of said mounting member coinciding with the axis of said mounting member cylinder, said contact member being pivotable about an axis thereof to concomitantly move the rollers mounted thereby toward and away from said opening, said second mounting member being yieldably biased about its pivot axis to yieldably urge the rollers carried thereby toward said opening and said second contact roller into yieldable engagement with said other side of said strip to form a seal therewith. 

1. In a seal for a housing having a gap therein through which strip material passes, the combination comprising: a. an elongated mounting member as long as the gap and pivotally mounted in said housing adjacent to said gap and yieldably urged to pivot in one direction about its pivot axis; b. elongated contact roller means rotatably mounted to said mounting member and yieldably urged toward said gap through said pivotal movement and yieldable urging of said mounting member for engaging the strip material to form a seal therewith; and c. elongated seal means extending the length of said elongated mounting member and carried thereby and contacting said contact roller means to form a seal between said mounting member and said contact roller means.
 2. A seal according to claim 1, wherein said seal means comprises a backup roller rotatably mounted to said mounting member.
 3. Apparatus according to claim 2, wherein said elongated seal means includes at least one seal between said backup roller and said mounting member.
 4. Apparatus according to claim 3, further including at least one elongated seal extending the length of said elongated mounting member between said mounting member and said housing.
 5. Apparatus for sealing the opening to a vacuum treatment chamber for strip, comprising: a. a frame having an opening defining said opening to the chamber; b. a pair of elongated mounting members at least as long as the maximum width of strip that can pass through said frame opening and pivotally mounted to said frame on opposite sides of said frame opening; c. a pair of contact rollers on opposite sides of said frame opening and rotatably mounted to said mounting members; d. a pair of backup rollers positioned on opposite sides of said frame opening and rotatably mounted to said mounting members and engaging said contact rollers, each contact roller being positioned between said frame opening and the associated one of said backup rollers; e. first seal means sealing the backup rollers to said mounting members; f. second seal means sealing said mounting members to said frame; and g. means yieldably urging said mounting members to pivot about the pivotal axes thereof so that said coNtact rollers mounted thereto are yieldably urged toward each other within said frame opening to yieldably engage said strip.
 6. In a seal for a wall structure having an opening therein through which strip material passes, the combination comprising: a. a contact roller on one side of said opening for engaging one side of said strip; b. a backup roller engaging said contact roller; and c. a mounting member for mounting said contact and backup rollers, said mounting member being pivotable about an axis thereof to concomitantly move the rollers mounted thereby toward and away from said opening, said mounting member being yieldably biased about its pivot axis to yieldably urge the rollers toward said opening and said contact roller into yieldable engagement with said one side of said strip to form a seal therewith.
 7. A seal according to claim 6, wherein the pivotal axis of said mounting member and the axes of rotation of said contact and backup rollers are parallel to each other and lie in a common plane.
 8. A seal according to claim 7, wherein the pivotal axis of said mounting member is further away from said opening than the axes of rotation of said contact and backup rollers.
 9. A seal according to claim 7, wherein the pivotal axis of said mounting member is between the axes of rotation of said contact and backup rollers.
 10. Apparatus according to claim 6, wherein said backup and contact rollers have their ends journaled in end portions of said mounting member.
 11. Apparatus according to claim 6, wherein said mounting member is cylindrical and includes channels longitudinally therein in which said contact and backup rollers are positioned.
 12. Apparatus according to claim 6, wherein said mounting member is cylindrical and includes end plates at the ends thereof, the pivotal axis of said mounting member coinciding with the axis of said mounting member cylinder, said contact roller being rotatably mounted to said end plates on one side of said cylindrical mounting member.
 13. Apparatus according to claim 6, including: a. a second contact roller on the other side of said opening for engaging the other side of said strip; b. a second backup roller engaging said second contact roller; and c. a second mounting member for mounting said second contact and backup rollers, said second mounting member being pivotable about an axis thereof to concomitantly move the rollers mounted thereby toward and away from said opening, said second mounting member being yieldably biased about its pivot axis to yieldably urge the rollers carried thereby toward said opening and said second contact roller into yieldable engagement with said other side of said strip to form a seal therewith. 